Clarification of molasses



Patented Mar. 30, 1937 UNITED STATES PATENT OFFICE 2,915,121 CLARIFIOAIION or MOLASSES Morris W. Mead, Jr., Bloomfield,

N. 1., asslgnor to National Grain Yeast Corporation, Belleville, N, J.

11 Claims.

The invention relates tothe clarification of molasses. The process described herein may be advantageously used wherever it is desired to purify molasses or to make a clear and brilliant molasses. It concerns especially the preparation of molasses suitable for use in the manufac- 1 ture of yeast by clarification thereof.

Raw molasses always contains certain impurities and suspended matter which are undesirable where it is used as a'nutrient in the propagation of yeast. Especially it contains certain ironand calcium compounds which aredetrimental when present in excess. Procedures have been suggested and used for treating molasses to remove such deleterious substances. One class of compounds used for clarification of molasses in the past has been the phosphates, that is, the various salts of ortho-phosphoric acid which are the commonest of the phosphates.

The object of the present invention is to provide a process which will give a more complete and economical removal of the impurities contained in molasses, in a shorter time and with the use of less material than any processes heretofore known. The procedure according to the of compounds of the metals such as iron and calcium. It also produces a quicker settling out of the impurities than previously used methods.

I have discovered that a special class of phosphates, namely, pyrophosphates, have unusually advantageous properties as compared to orthophosphates when applied to the clarification of molasses. Pyrophosphates are obtained by the removal of one molecule of water from two molecules or an ortho-phosphate. Pyrophosphoric acid has a chemical formula-of HiPaOm If a pyrophosphoric compound, that is, pyrophosphoric acid or one of its water soluble salts, is added to or dissolved in molasses it will produce a voluminous flocculent precipitation when the molasses is heated. The precipitate so produced settles to.the bottom quite rapidly, and the clear supernatant molasses may then be drawn ofl. v a

As compared with orthp-phosphates, a considerably reduced quantity of pyrophosphate is required, and yet such reduced quantity produces a considerably larger weight of precipitate.- In

other words, smaller quantities of pyrophosphate will give the same or better clarification than a larger quantity of ortho-phosphate. The precipitate is of such a nature as to carry down the matter suspended in the molasses more readily and more completely than that formed by an invention is particularly effective in the removal ortho-phosphate. This precipitate consists of insoluble compounds of certain metals which are present in molasses, together with organic radicals. The pyrophosphates are particularly effective in producing such compounds and thereby in removing excess quantities of the undesirable metals such as iron and calcium.

The general process is applicable both to beet and cane molasses. The. general procedure as applied to beet molasses, which as produced normally has a slightly alkalinereaction, is as follows: The raw molasses is diluted with water in the proportion of from 1 to 3 parts by weight of water to 1 part of molasses. A small-amount of an acid material, such as sulphuric acid, is added to the dilutedimass. Generally from 0.1% to 0.5% byweight on the raw molasses of concentrated sulphuric acid is sufficient. event it is desirable to bring the pH of the diluted molasses within a range of 52 to 5.8. However, the amount of acid may vary somewhat in accordance with the final acidity desired in the molasses, and in accordance with the type and amount of pyrophosphoric compound added, which will naturally aifect to some extent the acidity. In any event the beet molasses is preferably brought to a slightly acidic condition, since in this condition it is more easily purified.

Thereafter, a pyrophosphoric compound is added to the diluted mass and on heating a pre cipitate forms which settles quickly to the bottom. The clarified molasses which forms a supernatant layer may then be separated'from the sludge by decantation or in any other fashi0n.' For example, the precipitate may be filtered through a. filter press or in any other manner. It may be run through a centrifuge which is designed to separate the sludge. The use of filtration and centrifuge produces a particularly brilliant product.

Where cane molasses is used, which is normally slightly acidic; but which clarifies more readily when alkaline, the procedure is substantially the sameexcept that a suitable alkaline material isadded to ,bring the pH within the range of 8.0 to 8.5. In addition, a final filtration is desirable when clarifying cane molasses.

When the cane molasses is allowed to settle overnight, it is easy to separate a clear, supernatant liquid from the sludge. However, when this liquid is acidified a slight turbidity reappears, probably because of. the presence of very finelydispersed colloidal materials which become read- In any ily visible only in acid solution. On the other fied it remains brilliant even after the acidification. v

The specific procedure for carrying out the invention, and the increased clarification obtained thereby, will be made clear by the examples which follow:

Example 1 20 Example 2 Equal weights of four different phosphates were added to 500 cc. portions of raw beet molasses which had been diluted with 1.23 parts 25 of water and acidified. The amount of phosphate salt added for clarification purposes was in each case 1.0 gram. .The weightsof the solid residue obtained as a precipitate are indicated by the following table:

Sodium acid pyrophosphate ;grams 1.145. Potassium acid orthophosphate -do 0.362 Mono calcium orthophosphate. do 0.487 Commercial clarifie'n; do 0.428

(orthophosphoric acid and calcium orthophos- 3 phatel Eicample 3 The following is a preferred procedure for clarifying beet molasses:

A batch of raw beet molasses water in an amount by weight '1.23 times the weight of the molasses. It is'then acidified with 0.3% by weight on the raw molasses of sulphuric acid. 0.2% of sodium acid pyrophosphate 45 (NazHzPzOv) by weight on'the raw molasses is then dissolved in the acidified molasses at room temperature. The mixture is brought to a temperature of 90 C. to 100 C. During the heating a gradual formation of a fiocculent precipitate can be observed. The heating is discontinued when the required temperature is reached. The mixture is then allowed to stand for several is diluted with F in the case of pyrophos hours until the precipitate has completely settled.

The brilliant supernatant liquid which remains 55 is then decanted.

Example 4 The following is a typical procedure for cane molasses: v 3

Raw cane molasses is diluted with 1% times 60 its weight of water. Sufiicient lime isthen added to bring the pH to within. a range of 8.0 to'8. 5. 0.2% by weight on the raw molasses of sodium acid pyrophosphate is then added. The mass is heated to from 90 C. to 100 C.,- allowed to 65 settle, and the clear supernatant liquid decanted. The latter is filtered while still alkaline to avoid a slight turbidity which appears when the molasses is 'reacidified. v

The' amount of pyrophosphoric compound 70 which is added may vary considerably. Extremely satisfactory -clarifioation has been obtained within a range of from 0.1% to 1.5% by weight on the original raw molasses. precipitate apparently increases with a corre- .75 spending amount ofadded pyrophosphate up to The duantity of g in which 2.5 grams of precipitate is formed ro p about 1.0%. Above-1.0% the increase in the quantity of precipitate is relatively slight. For economical reasons, a quantity of 'pyrophosphate ranging from 0.1% to 0.5% on the raw molasses is most satisfactory. Larger amounts of pyro-. I

phosphate produce ificonveniently large quantities of sludge, without a proportionate gain in the amount of clarification, and are 'uneconomical. Within the range of 0.15% to 0.2% a sufficient and satisfactory settling out of the precipitate is obtained.

The acidity of the solution also affects the amount of precipitationobtained with pyrophosphate. In the treatment of beet molasses, excessive acidity will decrease the amount of precipitation. The following data represent tests sodium acid pyrophosphate was added to four 1900 cc. portions of diluted molasses at different acidities:

Dry weight Final pH of sludge 5. 74 2. 9 gm. 5. 50 2. 7 K 5. 20 2. s5 gni. 4. 97 2. 3 gm.

I have found that pyrophosphoric acid and its soluble salts are all effective in the clarification of molasses. Especially effective are the acid itself and sodium acid pyrophosphate, am- -monium pyrophosphate, and tetra-potassium pyrophosphate. The tetra-potassium pyrophosphate is even more active than the sodium acid pyrophosphate used in the examples described above.

The process above described produces a molas-.

ses' which is lighter in color-and somewhat more brilliant than that clarified with orthophos phates. It is very satisfactory for the-propagation of yeast, and good yields of yeast are obtained with its use which have good and baking quality,

'The procedure thereforeprovides an economical and .eflective method of clarifyingmolasses for yeast propagation or other purposes in a short'time and with the use of small quantities of materials. I

While I have descri d herein some embodi- "ments of my invention, I wish it to be understood that I do not intend to limit myself thereby except within the scope of the appended claims.

Iclaimz- '1. In a process of clarifying molasses, the steps of adding thereto a compound selected from the group consisting of pyrophosphoric acid and itssoluble salts, heating the molasses until a therein, and then separating the molasses from the precipitate.

2. In a process of clarifying molasses, the steps of adding thereto a compound selected from the consisting of pyrophosphoric acid and its soluble salts, heating the molasses until a precipitate is formed therein, allowing the precipitate to settle, and decanting the supernatant "liquid.

3. In a process of clarifying molasses, the steps of adding thereto'a compound selected from the of pyrophosphoric acid and its group consisting soluble salts, heating the m'olasses to a temper: ature of from 90 C. to 100 C., whereby a precipitate is formed ing the molasses from the precipitate.

4. In a process of clarifying beet molasses, the

steps of acidifying the beet molasses, adding color in the molasses, and separatthereto a compound selected from the group consisting of pyrophosphoric acid and its soluble salts, heating the molasses until a precipitate is formed therein, and then separating the molasses from the precipitate.

5. In a process of clarifying cane molasses, the steps of rendering the molasses alkaline, adding thereto a compound selected from the group consisting 'ofpyrophosphoric acid and its soluble salts, heating the molasses until a precipitate is formed therein, and then separating the molasses from the precipitate.

6. In a process of clarifying molasses, the steps of adding thereto from 0.1% to 1.5% of a compound selected from the group consisting of pyrophosphoric acid and its soluble salts, heating the molasses until a precipitate is formed therein, and separating the supernatant liquid from the precipitate.

'7. In a process of clarifying molasses, the steps of diluting the molasses with water, adding thereto a compound selected from the group consisting of pyrophosphoric acid and its soluble salts, heating the molasses until a precipitate is formed, and then separating the molasses from the precipitate.

8. In a process of clarifying molasses, the steps of diluting the molasses with from 1 to 3 parts by weight of water, dissolving in the diluted molasses from 0.1% to 1.5% of a compound selected from the group consisting of pyrophosphoric acid and its soluble salts, heating the molasses to from 90 C., to 100 0., whereby a precipitate is formed therein, allowing the precipitate to settle, and decanting the remaining supernatant liquid fromthe precipitate.

9. A process as claimed in claim 1, in which said compound is pyrophosphoric acid.

10. A process as claimed in claim 1, in which said compound is sodium acid pyrophosphate.

11. A process as claimed in claim 1, in which said compound is tetrapotassium pyrophosphate. 20

MORRIS W. MEAD, Jri. 

